Is CVE-2025-66281 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2025-66281 being exploited in the wild.

How severe is CVE-2025-66281?

Informational severity, with a CVSS score of 6.9, published 10 June 2026.

Which products and versions are affected?

QNAP Systems, Inc. QuTS hero h5.2.x prior to h5.2.9.3410 build 20260214; h5.3.x prior to h5.3.4.3500 build 20260520; h6.0.x prior to h6.0.0.3397 build 20260206.

Is there a fix for CVE-2025-66281?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2025-66281 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2025-66281?

Check whether you run QNAP Systems or Inc. QuTS hero at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2025-66281: QNAP QTS and QuTS hero NULL pointer dereference

CVE-2025-66281 · Severity: info · CVSS 6.9 · Published 2026-06-10

A vulnerability has been identified in QNAP operating systems used to manage Network Attached Storage (NAS) devices. A remote attacker could exploit this flaw to cause the system to crash or become unresponsive, leading to a denial-of-service. This impact prevents legitimate users from accessing stored data or using network services until the system is recovered.

Technologies: QNAP Systems, Inc. QuTS hero. Vendors: QNAP Systems, Inc..

Quick answers

Is CVE-2025-66281 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2025-66281 being exploited in the wild.
How severe is CVE-2025-66281?: Informational severity, with a CVSS score of 6.9, published 10 June 2026.
Which products and versions are affected?: QNAP Systems, Inc. QuTS hero h5.2.x prior to h5.2.9.3410 build 20260214; h5.3.x prior to h5.3.4.3500 build 20260520; h6.0.x prior to h6.0.0.3397 build 20260206.
Is there a fix for CVE-2025-66281?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2025-66281 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2025-66281?: Check whether you run QNAP Systems or Inc. QuTS hero at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A NULL pointer dereference (CWE-476) exists in several QNAP operating system versions, including QTS and QuTS hero. The vulnerability can be triggered by a remote attacker over the network without requiring authentication or user interaction. Successful exploitation leads to a denial-of-service (DoS) by causing the affected system component to crash. QNAP has released security updates for QTS 5.2.9, QuTS hero h5.2.9, h5.3.4, and h6.0.0 to address this issue.

Affected products

QNAP Systems, Inc. QTS 5.2.x versions prior to 5.2.9.3410 build 20260214
QNAP Systems, Inc. QuTS hero h5.2.x prior to h5.2.9.3410 build 20260214; h5.3.x prior to h5.3.4.3500 build 20260520; h6.0.x prior to h6.0.0.3397 build 20260206

Timeline

2026-06-10: disclosed
2026-06-10: advisory

References

https://www.qnap.com/en/security-advisory/qsa-26-10

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